The predatory
dinoflagellate Polykrikos kofoidii and parasitic dinoflagellate
Amoebophrya sp. both feed on the red-tide dinoflagellate Akashiwo
sanguinea in the Chesapeake Bay.P.
kofoidi may also prey upon A. sanguinea infected with Amoebophrya sp. and
thereby limit parasite success.To
further explore this trophic triangle, we conducted lab experiments to
test the hypothesis that P. kofoidii feeds preferentially on infected A.
sanguinea and grows better when given a diet of infected vs. uninfected
prey.Results showed that
P.kofoidiioffered infected A. sanguinea as prey grew at the same rate as
those offered uninfected prey.However,
in a mixture of infected and uninfected prey, P. kofoidii preferential
grazed uninfected A. sanguinea.Thus,
P. kofoidii and Amoebophrya sp. are in direct competition for uninfected
A. sanguinea.Together, they
may exert strong top-down control on A. sanguinea populations in the
Chesapeake Bay.